Ventricular Septal Defect

Ventricular septal defect (VSD) is one of the most common congenital heart defects, also known as hole in the heart. Practically there is a hole in the wall that separates the two ventricles of the heart, allowing oxygen-rich and oxygen-poor blood to mix.

Before birth, the right and the left lower chambers of the heart are not separate, but as the fetus grows, a wall forms between the ventricles. In VSD the wall does not completely form.

Anatomy

Ventricular Septal Defect can occur anywhere along the wall that separates the two lower chambers of the heart. They can be located at inlet, muscular, perimembranous, or outlet portions of the septum. The defects can be single, multiple or associated with other congenital heart diseases. An inlet Ventricular Septal Defect lies in the posterior portion of the ventricular septum beneath the tricuspid valve. A muscular VSD is located in the lower, muscular part of the ventricular septum and is the most common type of VSD, the perimembranous VSD being located in the upper part of the ventricular septum. A VSD of the outlet portion of the septum is located below the pulmonary and aortic valves.

Causes

Congenital heart defects often are caused by genetics or environmental factors which interfere with the normal development of the heart in a fetus, yet in many cases the reason remains unknown.

Some conditions during pregnancy are associated with increased risk of having a baby with VSD:

Rubella infection. Getting the German Measles during pregnancy increases the risk of fetal heart defects.

Genetic syndromes. Extra or missing chromosomes can cause VSD.

Drug or alcohol use during pregnancy can harm the development of the fetus.

Signs and symptoms

The symptoms associated with ventricular septal defects depend on the size of the defect. The defects which are observed in adult patients are usually small. The majority of patients with large defects come to medical or surgical attention early in life.

Patients having small VSDs usually present mild or no symptoms. In infant, usually a heart murmur is detected by a cardiologist during routine examination.

Babies with moderate VSDs may have excessive sweating or fatigue during feeds, shortness of breath, fast or heavy breathing, a lack of adequate growth, or frequent respiratory infections.

In large VSDs symptoms are similar to, but more severe than those noticed in moderate VSDs. In babies with a large VSD, symptoms may develop toward the end of the first month of life.

During a physical examination the doctor might hear a heart murmur. If a heart murmur or other signs are present, an echocardiogram is needed.

Diagnosis

If these signs and symptoms are present, an echocardiogram usually is done to confirm the diagnosis. Two-dimensional echocardiography, with Doppler echocardiography and color flow imaging provide information about structure of the heart, show how large the septal defect is, and how much blood is flowing through it.

The measurement of the left and right ventricle (LV and RV) diameters provide information about the size of the shunt, and about the volume of blood which is flowing through the shunt. The size of the defect is often expressed in terms of the size of the aortic root: large defects have about the size of the aortic root, moderate sized defects are one-third to two-thirds of the diameter of the aorta, and those that are less than one-third of the aortic root diameter are classified as small.

Complications

Complications of VSDs are the following:

growth failure

congestive heart failure

pulmonary vascular disease

Eisenmenger syndrome (process in which a left to right shunt in the heart causes increased flow in the pulmonary vessels, causing pulmonary hypertension, which means increased pressures in the right side of the heart, and reversal of the shunt into a right-to-left shunt)

viral or bacterial respiratory infections

aortic stenosis or regurgitation

Treatment

Sometimes observation is the only treatment needed, with regular checkups with the cardiologist. Children with small VSDs have an excellent long-term prognosis, they do not need neither medical, nor surgical therapy.

In children with moderate or large VSDs, only medical therapy is indicated, for symptom management, because many VSDs become smaller with time. When the symptoms of a VSD can’t be controlled with medical therapy or the baby is unable to grow, surgical closure of the defect is recommended.